1 files changed, 174 insertions, 0 deletions

diff --git a/editors/code/src/toolchain.ts b/editors/code/src/toolchain.ts
new file mode 100644
index 000000000..80a7915e9
--- /dev/null
+++ b/editors/code/src/toolchain.ts
@@ -0,0 +1,174 @@
+import * as cp from 'child_process';
+import * as os from 'os';
+import * as path from 'path';
+import * as fs from 'fs';
+import * as readline from 'readline';
+import { OutputChannel } from 'vscode';
+import { log, memoize } from './util';
+
+interface CompilationArtifact {
+    fileName: string;
+    name: string;
+    kind: string;
+    isTest: boolean;
+}
+
+export interface ArtifactSpec {
+    cargoArgs: string[];
+    filter?: (artifacts: CompilationArtifact[]) => CompilationArtifact[];
+}
+
+export class Cargo {
+    constructor(readonly rootFolder: string, readonly output: OutputChannel) { }
+
+    // Made public for testing purposes
+    static artifactSpec(args: readonly string[]): ArtifactSpec {
+        const cargoArgs = [...args, "--message-format=json"];
+
+        // arguments for a runnable from the quick pick should be updated.
+        // see crates\rust-analyzer\src\main_loop\handlers.rs, handle_code_lens
+        switch (cargoArgs[0]) {
+            case "run": cargoArgs[0] = "build"; break;
+            case "test": {
+                if (!cargoArgs.includes("--no-run")) {
+                    cargoArgs.push("--no-run");
+                }
+                break;
+            }
+        }
+
+        const result: ArtifactSpec = { cargoArgs: cargoArgs };
+        if (cargoArgs[0] === "test") {
+            // for instance, `crates\rust-analyzer\tests\heavy_tests\main.rs` tests
+            // produce 2 artifacts: {"kind": "bin"} and {"kind": "test"}
+            result.filter = (artifacts) => artifacts.filter(it => it.isTest);
+        }
+
+        return result;
+    }
+
+    private async getArtifacts(spec: ArtifactSpec): Promise<CompilationArtifact[]> {
+        const artifacts: CompilationArtifact[] = [];
+
+        try {
+            await this.runCargo(spec.cargoArgs,
+                message => {
+                    if (message.reason === 'compiler-artifact' && message.executable) {
+                        const isBinary = message.target.crate_types.includes('bin');
+                        const isBuildScript = message.target.kind.includes('custom-build');
+                        if ((isBinary && !isBuildScript) || message.profile.test) {
+                            artifacts.push({
+                                fileName: message.executable,
+                                name: message.target.name,
+                                kind: message.target.kind[0],
+                                isTest: message.profile.test
+                            });
+                        }
+                    } else if (message.reason === 'compiler-message') {
+                        this.output.append(message.message.rendered);
+                    }
+                },
+                stderr => this.output.append(stderr),
+            );
+        } catch (err) {
+            this.output.show(true);
+            throw new Error(`Cargo invocation has failed: ${err}`);
+        }
+
+        return spec.filter?.(artifacts) ?? artifacts;
+    }
+
+    async executableFromArgs(args: readonly string[]): Promise<string> {
+        const artifacts = await this.getArtifacts(Cargo.artifactSpec(args));
+
+        if (artifacts.length === 0) {
+            throw new Error('No compilation artifacts');
+        } else if (artifacts.length > 1) {
+            throw new Error('Multiple compilation artifacts are not supported.');
+        }
+
+        return artifacts[0].fileName;
+    }
+
+    private runCargo(
+        cargoArgs: string[],
+        onStdoutJson: (obj: any) => void,
+        onStderrString: (data: string) => void
+    ): Promise<number> {
+        return new Promise((resolve, reject) => {
+            const cargo = cp.spawn(cargoPath(), cargoArgs, {
+                stdio: ['ignore', 'pipe', 'pipe'],
+                cwd: this.rootFolder
+            });
+
+            cargo.on('error', err => reject(new Error(`could not launch cargo: ${err}`)));
+
+            cargo.stderr.on('data', chunk => onStderrString(chunk.toString()));
+
+            const rl = readline.createInterface({ input: cargo.stdout });
+            rl.on('line', line => {
+                const message = JSON.parse(line);
+                onStdoutJson(message);
+            });
+
+            cargo.on('exit', (exitCode, _) => {
+                if (exitCode === 0)
+                    resolve(exitCode);
+                else
+                    reject(new Error(`exit code: ${exitCode}.`));
+            });
+        });
+    }
+}
+
+/** Mirrors `ra_toolchain::cargo()` implementation */
+export function cargoPath(): string {
+    return getPathForExecutable("cargo");
+}
+
+/** Mirrors `ra_toolchain::get_path_for_executable()` implementation */
+export const getPathForExecutable = memoize(
+    // We apply caching to decrease file-system interactions
+    (executableName: "cargo" | "rustc" | "rustup"): string => {
+        {
+            const envVar = process.env[executableName.toUpperCase()];
+            if (envVar) return envVar;
+        }
+
+        if (lookupInPath(executableName)) return executableName;
+
+        try {
+            // hmm, `os.homedir()` seems to be infallible
+            // it is not mentioned in docs and cannot be infered by the type signature...
+            const standardPath = path.join(os.homedir(), ".cargo", "bin", executableName);
+
+            if (isFile(standardPath)) return standardPath;
+        } catch (err) {
+            log.error("Failed to read the fs info", err);
+        }
+        return executableName;
+    }
+);
+
+function lookupInPath(exec: string): boolean {
+    const paths = process.env.PATH ?? "";;
+
+    const candidates = paths.split(path.delimiter).flatMap(dirInPath => {
+        const candidate = path.join(dirInPath, exec);
+        return os.type() === "Windows_NT"
+            ? [candidate, `${candidate}.exe`]
+            : [candidate];
+    });
+
+    return candidates.some(isFile);
+}
+
+function isFile(suspectPath: string): boolean {
+    // It is not mentionned in docs, but `statSync()` throws an error when
+    // the path doesn't exist
+    try {
+        return fs.statSync(suspectPath).isFile();
+    } catch {
+        return false;
+    }
+}